1. Field of the Invention
The present invention relates to a stacked package module and, more particularly, to a stacked package module which can enhance the elasticity of conductive pad layout and the electro-connecting region.
2. Description of Related Art
In the development of electronics, the design trend of electronic devices is towards multifunction and high-performance. Thus, high-density integration and miniaturization are necessary for a semiconductor package structure. On the ground of reason aforementioned, the mono-layered circuit boards providing electrical connections among active components, passive components, and circuits, are being replaced by the multi-layered circuit boards. The area of circuit layout on the circuit board increases in a restricted space by interlayer connection to meet the requirement of high-density integrated circuits.
In general, a conventional semiconductor package structure is made such that a semiconductor chip is mounted by its back surface on the top surface of the substrate, then the package structure is finished through wire bonding, or a semiconductor chip is mounted by the active surface thereof on the top surface of the substrate, thereby finishing a flip-chip package structure, followed by placing solder balls on the back surface of the substrate to provide electrical connections for an electronic device like a printed circuit board.
FIG. 1 shows a conventional wire bonding package structure. The wire bonding package structure 1 comprises a circuit board 10, a chip 11, a plurality of metal wires 14, and a molding material 15. The circuit board 10 has a first surface 10a having a plurality of wire bonding pads 101 and an opposite second surface 10b having a plurality of solder pads 102. In addition, the circuit board 10 has a cavity 105, and the chip 11 is disposed in the cavity 105. The active surface 11a of the chip 11 has a plurality of electrode pads 111, electrically connecting to the wire bonding pads 101 of the circuit board 10 by the metal wires 14. The cavity 105 of the circuit board 10 is filled with the molding material 15, and the molding material 15 wraps the chip 11 and the metal wires 14. The solder pads 102 of the circuit board 10 can electrically connect with an electronic device (not shown) by solder balls 16.
FIG. 2 shows a stacked package module comprising the aforementioned package structure. The stacked package module is accomplished by stacking two same package structures 1 and 1′ as shown in FIG. 1. The solder pads 102‘on the surface 10b’ of the upper package structure 1′ electrically connect with the conductive pads 103 on the surface 10a of the lower package structure 1 by a plurality of solder balls 203.
However, in the above module comprising a plurality of stacked package structures, only the remaining region of the substrate of each package structure, where no semiconductor chip is disposed, can suffice conductive pads for electrically connecting with another package structure by solder balls. It is indicated that the electrical connecting area on the substrate of each package structure is limited, and thereby the number and the layout of I/O connections of each package structure is limited, resulting in reduced elasticity of circuit layout on the substrate and design flexibility of the package structure.
In addition, soldering is the only method for electrically connecting the aforementioned package structure with an electronic device, resulting in nondetachable electrical connections.
Accordingly, the purpose of the present invention is to provide a package structure having characteristics of compact size, high performance, high flexibility, and detachability.